Ultrasound is useful not only as a modality to detect and diagnose abnormalities, but also as a way to guide interventions such as biopsies, vascular access, tumor ablations, and drainage of fluid collections, body cavities, bile ducts, the urinary tract, and so on. FIG. 1 is an illustration of an ultrasound-guided biopsy as currently practiced. An ultrasound probe 1000 is placed against the skin of a patient in a location overlying a target 1002 within the body of the patient, so that ultrasound energy can be directed to the target for use in ultrasonic imaging of the target 1002 according to known principles.
A needle 1004 is advanced through the skin 1006 of the patient and is advanced toward the target 1002 and into the target 1002 with visual guidance provided by viewing the ultrasound imaging provided by the ultrasound probe 1000. The needle 1004 can be visualized in the ultrasound image from the time that it enters the ultrasound beam 1008 so that the image is useful in guiding the needle to the location of the target 1002, as the operator can manually make adjustments to the path along which the needle 1004 takes in reaching the target 1002.
Guiding the needle 1004 into the desired structure (i.e., target 1002) is a skill that requires the operator to decide on the best path to the target 1002 and insert the needle 1004 along that path. This process is greatly facilitated by lining up the needle 1004 in the plane of the ultrasound beam 1002. When the needle is in this plane, it appears as a straight, echogenic (bright) structure with a predictable trajectory toward the target, such as shown in FIG. 2. When the needle 1004 is not in this plane, it may appear as a bright dot where it crosses the ultrasound beam 1008 or not at all if it is completely outside the ultrasound beam 1008. In the case where the needle 1004 and its path are not seen in the ultrasound image, or is seen as crossing the ultrasound image, there is a risk that the needle 1004 may have passed through some unforgiving non-target anatomical structure.
The task of positioning the needle 1004 in the correct plane (plane of the ultrasound beam 1008) can be difficult because the ultrasound probe is a curvy hand-held device and the beam 1008 is not visible to the naked eye. The operator must estimate where the beam 1008 will be, insert the needle 1004, and readjust as necessary based on the appearance of the image. Gaining proficiency with this takes time and experience as it involves approximation, abstract thinking, and hand-to-image coordination. Lining up the needle 1004 can be done with the aid of a metallic or molded plastic guide, but most experienced operators do not use guides because they are expensive, clunky, easy to lose, and restrict the ability to reposition the needle 1004 pathway that the needle travels along. Also, since they clamp on the outside of the ultrasound probe, they must be discarded or re-sterilized between uses. Instead, most experienced operators work “free hand”, relying on their many hours of experience and even so often endure repeated readjustments of the needle 1004 and ultrasound probe 1000 to reach the target 1002.
Because of these issues, various attempts have been made in the past to help facilitate the process of aligning the needle with the ultrasound beam and, ultimately, the target.
Ma et al., U.S. Patent Application Publication No. 2011/0245659 discloses a laser emitter 22 on an instrument portion 19 such as a syringe that is used to hold needle 14. Laser light emitted from the laser emitter 22 can be received or reflected by the receiver/reflector 23 on the ultrasound device 21. The transducers 22 and 23 are adapted to operate cooperatively to provide information regarding the depth of the tip of the instrument. Ma et al. also uses a needle guide 13 which restricts the location at which the needle can be inserted into the patient to a very small locus. Although one of the position transducers may comprise a reflector or other passive element, the invention of Ma et al. nevertheless requires specialized instrumentation, in addition to the ultrasound transducer and its position transducer, in order to be operable. Also, the calculations performed by the Ma et al. invention are focused on the depth of the tip of the instrument and do not provide information as to the accuracy of alignment of the needle 14 with the plane of the ultrasound imaging, as the guide 13 is used to provide information with respect to the orientation of the instrument with respect to the imaging transducer 21.
Brooks et al., US. Patent Application Publication No. 2008/0027325 discloses an ultrasound apparatus with a light source that emits a broad planar light beam that is coplanar with the target plane of the ultrasound beam. The needle is inserted into the plane of the laser beam so as to be collinear with the target beam. The operator can monitor light reflected from the needle to align the needle appropriately. However this requires the operator to take his eyes away from viewing the ultrasound image as the operator views the needle to see if light is reflecting off it. The operator must switch between viewing the needle directly and viewing the ultrasound image to coordinate both maintaining the needle in alignment with the light plane and observing the tip of the needle as it approaches the target. This requires additional skill and experience, as the operator must steady the needle position and have a good memory of the hand-to-eye coordination that was required to maintain that position of the needle upon viewing it, as the operator switches from viewing the needle directly to viewing the target on the ultrasound image. It can be difficult to maintain the orientation of the needle upon switching back and forth between views.
Sauer et al., U.S. Pat. No. 6,689,067 discloses an ultrasound probe 12 having a mounting unit 16 to which a laser light source 22 is affixed. The light source 22 can project a beam that is coplanar with the ultrasound imaging plane 4. A needle can be inserted into the skin of a patient along the laser line projected on the skin. The user can see if the needle is aligned with the laser beam plane/ultrasound imaging plane 4 by seeing a reflection of the light beam 3 off the surface of the needle. However this requires the operator to take his eyes away from viewing the ultrasound image as the operator views the needle to see if light is reflecting off it. The operator must switch between viewing the needle directly and viewing the ultrasound image to coordinate both maintaining the needle in alignment with the light plane and observing the tip of the needle as it approaches the target. This requires additional skill and experience, as the operator must steady the needle position and have a good memory of the hand-to-eye coordination that was required to maintain that position of the needle upon viewing it, as the operator switches from viewing the needle directly to viewing the target on the ultrasound image. It can be difficult to maintain the orientation of the needle upon switching back and forth between views. In another embodiment, an augmented reality system is used to see both the optical light beam or an optical image with overlaid markers and the patient at the same time. This involves a half silvered mirror and mounting elements which add to the expense and complexity of the apparatus.
There is a continuing need for improvements for facilitating the insertion and guidance of a needle into a desired target within a body with the assistance of imaging.
It would be beneficial to provide such improvements so that they can be used with needles that do not require additional specialized features or instrumentation to be used with the guidance system.
It would be further desirable to provide improvements that can be used to adapt existing imaging instrumentation for use in carrying out improved placement and/or guidance.